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Frequently Asked Questions (FAQ)

What methods are available on a client?

The AWS SDK for PHP utilizes service descriptions and dynamic magic __call() methods to execute API operations. Every magic method supported by a client is documented in the docblock of a client class using @method annotations. Several PHP IDEs, including PHPStorm and Zend Studio, are able to autocomplete based on @method annotations. You can find a full list of methods available for a web service client in the API documentation of the client or in the user guide for that client.

For example, the Amazon S3 client supports the following operations: Creating a bucket

What do I do about a cURL SSL certificate error?

This issue can occur when using an out of date CA bundle with cURL and SSL. You can get around this issue by updating the CA bundle on your server or downloading a more up to date CA bundle from the cURL website directly.

Simply download a more up to date CA bundle somewhere on your system and instruct the SDK to use that CA bundle rather than the default. You can configure the SDK to use a more up to date CA bundle by specifying the ssl.certificate_authority in a client's factory method or the configuration settings used with Aws\Common\Aws.

$aws = Aws\Common\Aws::factory(array(
    'region' => 'us-west-2',
    'ssl.certificate_authority' => '/path/to/updated/cacert.pem'

You can find out more about how cURL bundles the CA bundle here:

How do I disable SSL?


Because SSL requires all data to be encrypted and requires more TCP packets to complete a connection handshake than just TCP, disabling SSL may provide a small performance improvement. However, with SSL disabled, all data is sent over the wire unencrypted. Before disabling SSL, you must carefully consider the security implications and the potential for eavesdropping over the network.

You can disable SSL by setting the scheme parameter in a client factory method to 'http'.

$client = Aws\DynamoDb\DynamoDbClient::factory(array(
    'region' => 'us-west-2',
    'scheme' => 'http'

How can I make the SDK faster?

See Performance Guide for more information.

Why can't I upload or download files greater than 2GB?

Because PHP's integer type is signed and many platforms use 32-bit integers, the AWS SDK for PHP does not correctly handle files larger than 2GB on a 32-bit stack (where "stack" includes CPU, OS, web server, and PHP binary). This is a well-known PHP issue. In the case of Microsoft® Windows®, there are no official builds of PHP that support 64-bit integers.

The recommended solution is to use a 64-bit Linux stack, such as the 64-bit Amazon Linux AMI with the latest version of PHP installed.

For more information, please see: PHP filesize :Return values.

How can I see what data is sent over the wire?

You can attach a Guzzle\Plugin\Log\LogPlugin to any client to see all request and response data sent over the wire. The LogPlugin works with any logger that implements the Guzzle\Log\LogAdapterInterface interface (currently Monolog, ZF1, ZF2).

If you just want to quickly see what data is being sent over the wire, you can simply attach a debug log plugin to your client.

use Guzzle\Plugin\Log\LogPlugin;

// Create an Amazon S3 client
$s3Client = S3Client::factory();

// Add a debug log plugin

For more complex logging or logging to a file, you can build a LogPlugin manually.

use Guzzle\Log\MonologLogAdapter;
use Guzzle\Plugin\Log\LogPlugin;
use Monolog\Logger;
use Monolog\Handler\StreamHandler;

// Create a log channel
$log = new Logger('aws');
$log->pushHandler(new StreamHandler('/path/to/your.log', Logger::DEBUG));

// Create a log adapter for Monolog
$logger = new MonologLogAdapter($log);

// Create the LogPlugin
$logPlugin = new LogPlugin($logger);

// Create an Amazon S3 client
$s3Client = S3Client::factory();

// Add the LogPlugin to the client

You can find out more about the LogPlugin on the Guzzle website:

How can I set arbitrary headers on a request?

You can add any arbitrary headers to a service operation by setting the command.headers value. The following example shows how to add an X-Foo-Baz header to an Amazon S3 PutObject operation.

$s3Client = S3Client::factory();
    'Key'    => 'test',
    'Bucket' => 'mybucket',
    'command.headers' => array(
        'X-Foo-Baz' => 'Bar'

Does the SDK follow semantic versioning?

Yes. The SDK follows a semantic versioning scheme similar to – but not the same as – semver. Instead of the MAJOR.MINOR.PATCH scheme specified by semver, the SDK actually follows a scheme that looks like PARADIGM.MAJOR.MINOR where:

  1. The PARADIGM version number is incremented when drastic, breaking changes are made to the SDK, such that the fundamental way of using the SDK is different. You are probably aware that version 1.x and version 2.x of the AWS SDK for PHP are very different.
  2. The MAJOR version number is incremented when breaking changes are made to the API. These are usually small changes, and only occur when one of the services makes breaking changes changes to their API. Make sure to check the CHANGELOG and UPGRADING documents when these changes occur.
  3. The MINOR version number is incremented when any backwards-compatible change is made, whether it's a new feature or a bug fix.

The best way to ensure that you are not affected by breaking changes is to set your dependency on the SDK in Composer to stay within a particular PARADIGM.MAJOR version. This can be done using the wildcard syntax:

    "require": {
        "aws/aws-sdk-php": "2.4.*"

...Or by using the the tilde operator. The following statement is equivalent to >=2.4.9,<2.5:

    "require": {
        "aws/aws-sdk-php": "~2.4.9"

See the Composer documentation for more information on configuring your dependencies.

The SDK may at some point adopt the semver standard, but this will probably not happen until the next paradigm-type change.

Why am I seeing a "Cannot redeclare class" error?

We have observed this error a few times when using the aws.phar from the CLI with APC enabled. This is due to some kind of issue with phars and APC. Luckily there are a few ways to get around this. Please choose the one that makes the most sense for your environment and application.

  1. Disable APC for CLI - Change the apc.enable_cli INI setting to Off.
  2. Tell APC not to cache phars - Change the apc.filters INI setting to include "^phar://".
  3. Don't use APC - PHP 5.5, for example, comes with Zend OpCache built in. This problem has not been observed with Zend OpCache.
  4. Don't use the phar - You can install the SDK through Composer (recommended) or by using the zip file.

What is an InstanceProfileCredentialsException?

If you are seeing an Aws\Common\Exception\InstanceProfileCredentialsException while using the SDK, this means that the SDK was not provided with any credentials.

If you instantiate a client without credentials, on the first time that you perform a service operation, the SDK will attempt to find credentials. It first checks in some specific environment variables, then it looks for instance profile credentials, which are only available on configured Amazon EC2 instances. If absolutely no credentials are provided or found, an Aws\Common\Exception\InstanceProfileCredentialsException is thrown.

If you are seeing this error and you are intending to use instance profile credentials, then you need to make sure that the Amazon EC2 instance that the SDK is running on is configured with an appropriate IAM role.

If you are seeing this error and you are not intending to use instance profile credentials, then you need to make sure that you are properly providing credentials to the SDK.

For more information, see Providing Credentials to the SDK.